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Chapter 1: Problem 57

$$4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \rightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)$$ The above reaction will experience a rate increase by the addition of a catalyst such as platinum. Which of the following best explains why? (A) The catalyst causes the value for \(\Delta G\) to become more negative. (B) The catalyst increases the percentage of collisions that occur at the proper orientation in the reactant molecules. (C) The catalyst introduces a new reaction mechanism for the reaction. (D) The catalyst increases the activation energy for the reaction.

Short Answer

Expert verified
(C) The catalyst introduces a new reaction mechanism for the reaction.

Step by step solution

01

Role of a catalyst

Recall that a catalyst is a substance that speeds up a chemical reaction without being consumed in the process. It does so by providing an alternate reaction pathway with a lower activation energy, meaning that less energy is required to get the reaction started.
02

Evaluate the given options

Now, let's evaluate each of the given options. (A) A catalyst does not change \(\Delta G\), the change in free energy of the reaction, it merely makes it easier for the reaction to occur. Therefore, this option is incorrect. (B) While catalysts do facilitate reactions, they don't necessarily increase the 'proper orientation' of reactant molecules. They lower the energy barrier for the reaction to proceed. Thus, this option is not correct. (D) Catalysts do not increase the activation energy for a reaction. Instead, they decrease it. Thus, this option is incorrect.
03

Choose the correct option

Based on the process of elimination and our understanding of catalysts, we arrive at option (C). The catalyst introduces a new reaction mechanism for the reaction. This is indeed what a catalyst does: it provides an alternate pathway for the reaction to proceed, which typically has a lower activation energy.

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Most popular questions from this chapter

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